<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<script>

    Animal.prototype.firstName = '你好';
    function Animal() {
        this.name = "余金港";
    }
    var animal = new Animal();//创建对象

    
    var person = new Person();//创建对象
    Person.prototype = animal;
    function Person() {
        this.age = 19;
    }

    Student.prototype = person;
    function Student() {
        this.sex = "男";
    }
    var student = new Student();
   


</script>

</body>
</html>

